Design and Fabrication of Metamaterial Loaded Microstrip Patch Antenna for Radar Cross Section Reduction

Abstract

Radar cross section reduction (RCSR) has been prompted due to evolution of military technology. This thesis reviews the basic concepts and characteristics of metamaterials, as these are the most favourable development that impact defence industry products and stealth technology. It emphasizes the role of airpower and the ever-increasing demand of stealth. Initially, the blending of the fundamental aspects of stealth technology through radar signatures and methods of signature reduction are discussed. It also explores the recent research activities on metamaterials in various areas. Some existing research techniques used for RCSR are examined. The metamaterials are engineered media whose electromagnetic responses depend on their composition as well as on their structure. The general benefits of metamaterials are pointed in the thesis. Metamaterials are mostly used in antenna configuration for enhancing antenna performance such as realizing miniaturization, expanding operating band, enhancing gain as well as reducing RCS. The characteristics of the metamaterials like negative permeability and negative permittivity are basically the reason why MMs should be used in stealth technology. The various categories of metamaterials used for RCSR are studied in thesis. In this thesis we have also proposed a unit cell of metamaterial. Metamaterial unit cell consist of square loop and intersecting strips at the edges of add shaped structure. In this thesis, primary antenna used is microstrip patch antenna. The microstrip patch antenna is having dimension 66x66

and substrate height of 2mm, fabricated on FR-4. Another microstrip antenna is proposed for attainment of enhanced RCSR. A metamaterial loaded antenna is proposed for this application, which operates over frequency range of 2-18 GHz. The metamaterial unit cell is replicated eight times to form ground of proposed microstrip patch antenna. Coaxial feed technique is used which gives freedom to optimize impedance matching easily. Parametric analysis and simulation results validate that the metamaterial used on microstrip patch antenna enhances the RCSR. Along with the RCS, different properties of antenna i.e. return loss and surface current are studied. The simulated and measured results of fabricated prototype unveil that the suggested work is suitable for RCSR application.